Pipeline laying system and vessel

ABSTRACT

A pipelaying system is adapted for deployment on a vessel for use in a body of water. The system has at least one reel for storage and layout of a rigid walled pipeline, a pipeline support comprising a pipe takeoff drum for mounting on the vessel for rotation about a horizontal drum axis, a pipe takeoff structure pivotally mounted on the axis of rotation of the drum, and a drive unit operably connected to the reel. Such an arrangement is adapted to permit control of the rate of layout of the pipeline.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.757,790, filed July 22, 1985, now abandoned, which is acontinuation-in-part of U.S. patent application Ser. No. 646,112, filedAug 31, 1984, now U.S. Pat. No. 4,687,376, for Multi-Reel OperationalLines Laying vessel, which is hereby incorporated by reference as thoughfully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a reel pipelaying system and vessel on whichat least one reel is disposed for laying a pipeline in waters havingdepths limited only by the strength of the pipe. More particularly, theinvention pertains to a new type of pipeline layout system and vessel inwhich at least one reel is employed for storing and unspooling a rigidwalled pipeline. The laying system provides for the layout of a pipelinefrom any one of a plurality of reels and for the adjustment of waterentry angles over a wide angular range.

The vessel of this invention is designed to accommodate a permanentlymounted pipe spooling main reel which is of substantial size and iscapable of spooling pipe up to 16 inches in diameter. The laying systemis stern mounted for handling the layout during unspooling from thispermanently mounted main reel or from auxiliary storage reels.

2. History of the Prior Art

In laying offshore subsea pipelines for such uses as the gathering ofoil and/or gas from offshore wells, as, for example, in the Gulf ofMexico, it has been conventional to use one of two main methods to lal,the pipe. In the first, called the "stovepiping" method, a pipeline isfabricated on the deck of a lay barge by welding together individuallengths of pipe as the pipe is laid out from the barge. Each length ofpipe is about 40' or 80' long. Thus, the pay-out operation must beinterrupted periodically to permit new lengths of pipe to be welded tothe string. The stovepiping method requires that skilled welders andtheir relatively bulky equipment accompany the pipelaying barge crewduring the entire layout operation; all welding must be carried out onsite and often under adverse weather conditions. Further, thestovepiping method is relatively slow, with experienced crews being ableto lay only one to two miles of pipe a day. This makes the entireoperation subject to weather conditions which can cause substantialdelays and make working conditions quite harsh.

The other principal conventional method is the reel pipelayingtechnique. In this method, a pipeline is wound on the hub of a reelmounted on the deck of a lay barge. Pipe is generally spooled onto thereel at a shore base. At such a shore base, short lengths of pipe can bewelded under protected and controlled conditions to form a continuouspipeline which is spooled onto the reel. The lay barge is then towed toan offshore pipelaying location and the pipeline is spooled off the reelbetween completion points. This method has a number of advantages overthe stovepiping method, among them, speed (one to two miles per houradvantage); lower operating costs, e.g., smaller welding crews and lesswelding equipment must be carried on the lay barge; and less weatherdependency.

The broad concept of reel pipelaying was also disclosed in BritishPatent No. 601,103 (Ellis), issued Apr. 28, 1948, wherein it wassuggested that lengths of pipe be joined together at the manufacturingplant and coiled onto a drum and mounted on a barge or ship; the loadedbarge would then be moved to the desired marine location and the pipeunwound from the drum by fixing one end of the pipe and towing the bargeaway from the fixed locaiion.

After a hiatus of about thirteen years, research into the reelpipelaying technique was renewed and was carried on by Gurtler, Herbert& Co., Inc. of New Orleans, La. By 1961 that company had sufficientlyadvanced the reel pipelaying technique to make it a commerciallyacceptable and viable method of laying pipe in the offshore petroleumindustry, able to compete with the traditional stovepiping technique.The first known commercial pipelaying reel barge, called the U-303, wasbuilt by Aquatic Contractors and Engineers, Inc., a subsidiary ofGurtler, Herbert, in 1961. The U-303 utilized a large vertical axisreel, permanently mounted on a barge and having horizontally orientedflanges (generally referred to in the trade as a "horizontal reel"). Acombined straightener-level winder was employed for spooling pipe ontothe reel and for straightening pipe as it was unspooled. The U-303 firstlaid pipe commercially in September 1961 in the Gulf of Mexico off thecoast of Louisiana and was used successfully during the 1960's to layseveral million linear feet of pipe of up to 6" diameter. The U- 303reel pipelaying barge is described in U.S. Pat. Nos. 3,237,438 (Tesson)and 3,372,461 (Tesson) both assigned to the assignee of the inventionhereof.

The successor to the U-303 currently in use in the Gulf of Mexico andknown in the trade as the "Chickasaw" also utilizes a large horizontalreel, permanently mounted to the barge such that it is not readilymoveable from one carrier vessel to another. Various aspects of"Chickasaw" are designed in the following U.S. patents, all assigned tothe assignee of the invention hereof:

Sugasti, et al.--U.S. Pat. No. 3,630,461

Gibson--U.S. Pat. No. 3,651,778

Mott, et al.--U.S. Pat. No. 3,680,342

Key, et al.--U.S. Pat. No. 3,712,100

The Gibson patent shows an apparatus for diverting a single pipelinefrom a horizontal unspooling direction to a vertical direction forlayout in a body of water. The patent describes very simple unspoolingtools which do not provide for certain important pipeline handlingfunctions.

U.S. Pat. No. 3,685,306 to Mott also describes an apparatus whichdiverts a single pipeline from a horizontal position to a fixed verticaldirection. The pipeline can be successively unreeled from adjacentganged reels, but the water entry angle cannot be adjusted to permitlayout in variable water depths.

Commercial reel pipelaying techniques require the use of certain pipehandling equipment in addition to the reel. Among such pipe handlingequipment usually employed in commercial reel pipelaying systems is astraightener mechanism. This may take the form of a series of rollers ortracks, or other arrangement which imparts sufficient reverse bendingforce to the pipe to remove residual curvature so that after unspooling,the pipe will lay substantially straight on the sea bottom.

Other pipe handling equipment used in commercial reel pipelaying systemsmust be provided for facilitating pipeline adjustments, particularly forinspecting pipeline coatings and repairing the same. Valves must beinserted into the pipeline at various lengths and for this operationpipe clamping and holding equipment is provided. Various sacrificialanodes, survey markers, transponders and floats must also be attached tothe pipeline in a pipe handling station for many projects. Commercialreel pipelaying systems also provide equipment for making connectionswith and to existing pipeline structures. For making such connectionspipe clamping means are required.

U.S. Pat. No. Re. 30,846 (Lang et al) describes an apparatus for layingpipeline from a vertical reel in which the pipe conditioning apparatusis pivotable to adjust the lift-off angle of the pipe relative to thehorizontal plane (e.g., the deck of a ship) as a function of the waterdepth in which the pipe is being laid. This has distinct commercialadvantages, especially where the reel pipelaying system is incorporatedinto a self-propelled ship, such as that of the present invention,capable of traveling to different job sites, having different pipe sizeand/or laying depth requirements.

An early concept for a reel pipelaying ship is described in Goren, etal. "The Reel Pipelay Ship--A New Concept" Offshore TechnologyConference Proceedings, May 1975 (Paper No.--OTC 2400). This paper(hereafter the Goren, et al 1975 OTC Paper) describes advantages andoperating features of a proposed reel pipelaying ship. However, the costof construction of a ship as described in that paper was estimated to beon the order of $100,000,000.

APACHE REEL LAYING VESSEL

The research and development work for the ship described in the Goren,et al paper, (done at great expense by and on behalf of the assignee ofthis application) was subsequently materially revised in numerous majorrespects, and substantial changes and improvements were made to achievethe design of a substantially different reel pipelaying ship which isdescribed in the following U.S. patents, all assigned to the assignee ofthe invention hereof:

Springett, et al--U.S. Pat. No. 4,230,421

Uyeda, et al--U.S. Pat. No. 4,269,540

Yenzer, et al--U.S. Pat. No. 4,297,054

Springett, et al--U.S. Pat. No. 4,340,322

Uyeda, et al--U.S. Pat. No. 4,345,855

The disclosures of these five single reel patents are herebyincorporated as though fully set forth herein.

The vessel described in these patents was constructed and is currentlyin use in various offshore oil fields and is known in the offshore oilindustry as the "Apache." This vessel is a self-propelled dynamicallypositioned single reel pipelaying ship which has a specially constructedhull comprising a reel support structure for rotatably mounting avertical reel for unspooling a rigid walled pipeline. A single pipelineis handled by this ship. Other pipe handling equipment included are apipe bending radius controller; pipe straightening equipment; clampingassembly; a stern pipe guide assembly and a level wind assembly. Atensioning assembly is also arranged on a support ramp assembly. Thepipe exit angle or the water entry angle can be varied from 18° to about60° since this is the range of angular movement of the support rampassembly. The upper part of this range of the pipe water entry angles issufficient to accommodate laying a single pipeline in approximately3,000 ft. water depth. In order to lay pipe at greater depths it isnecessary to increase the pipe water entry angle.

The Apache vessel does not have adequate unused deck space to permit theconvenient placement of auxiliary reels. An early suggestion which wasmade during the vessel's construction phase and mentioned in the abovepatents was that portable reels could be placed on the Apache deck topermit stern bundling of smaller lines with the pipeline from the mainreel. These smaller lines were not to be passed through the pipehandling equipment with the main reel pipeline according to thesuggestion. This stern bundling suggestion was made in the OTC Paper No.3069, May 8-11, 1978.

There are increasing requirements in the offshore petroleum industry forlaying pipelines in deep water at depths greater than 3,000 feet and inremote areas far from supply bases. To be commercially viable apipelaying vessel must also be capable of laying pipelines in shallowwater of less than 200 feet up to over 3,000 feet in depth. Thepipelaying system and support vessel of this invention represents a newand different concept to meeting these needs.

The vessel utilized with the pipelaying system of this invention can bea self-propelled dynamically positioned ship or it can be a barge whichrequires a tug for motive power. The vessel deck is utilized to mountauxiliary reels for the layout of additional operational lines whenneeded.

A principal feature of the present pipelaying system is that a pipelinelaying device is mounted adjacent to the stern of the vessel. Thepipeline laying device includes a pipeline support means for providingsimultaneous moving contact for the pipeline and also includes a pipetake-off structure which moves arcuately about the perimeter orperiphery of the supporting means. The pipe take-off structure supportsa pipe handling means which facilitates the making of certain commercialrequired pipeline adjustments and connections. A pipeline is unspooledfrom one of the storage reels mounted on the vessel and moved into thelaying device where it comes into frictional contact with the pipelinesupport means which is adapted for providing moving contact for thepipeline. The preferred laying device of the present invention changesthe direction of movement of the pipeline from horizontal to a range ofangles up to about 90° (vertical) and can be thus used for layingpipelines in shallow waters of under 200 feet down to much greaterdepths of 7,500 feet and beyond.

The preferred pipeline laying device also includes straightening andtensioning devices which are adapted to straighten and provide tensionfor the pipeline. The straightening means is adapted for imparting areverse bending force to the rigid walled pipeline.

The preferred pipeline laying system has a pipeline laying device ortake-off assembly mounted adjacent to the stern of the vessel. Thetake-off assembly includes a rotatably mounted drum and a pipe take-offstructure which can preferably contain straightening and tensioningdevices as well as additional pipe clamping means. The pipe take-offdrum in the laying device is not powered by a separate motive means butrather is rotated by the frictional contact between the pipeline withthe periphery of the drum which is adapted to function as a pipelinesupport means.

The take-off structure is rotatably journaled for arcuate movement at apredetermined distance spaced from the perimeter or periphery of thetake-off drum. This pipe take-off structure permits water entry anglesfor the pipeline of from about 20° to 90° so as to permit lay out oflines at depths of about 200 feet to much greater depths. The upper partof this range from about 60° to 90° is used for deep water laying in3,000 feet and greater depths.

Level wind carriages are also preferably provided for mounting thepipeline laying device so that it can move transversely across thevessel deck as the pipeline is being unspooled from the storage reel.

The pipeline take-off structure includes pipe handling means whichfacilitate making pipeline adjustments and connections which arerequired for commercial pipelaying. Such pipe handling means includesthe provision of a work platform from which the pipeline coating can beinspected and repaired, when necessary, and from which valves can beinserted into the pipeline after it is cut through and from whichvarious sacrificial anodes, survey markers, transponders and floats canbe attached to the pipeline as it is unspooled and laid out. Anotherpipe handling means included in the pipeline take-off structure is apipe clamping means and a pipeline adjustment means for use in makingconnections to existing recovered pipelines. Abandonment and recovery(A/R) equipment is also placed in the take-off structure.

The laying device can be arranged to cooperate with a straighteningdevice contained within the pipe take-off structure so as to contributeone of three force imposition zones directed to the rigid walledpipeline in order to reverse bend the pipeline in the opposite directionto the curvature imparted by the storage reel.

In this embodiment it is possible to use the hydraulic braking systemson the storage reel hydraulic motors to provide tensioning of thepipeline, thus permitting pipe layout in the absence of separatestraightening and/or tensioning devices. The laying device and thepipeline storage reel together with the associated straightening andtensioning devices and level wind carriages form a pipeline layoutsystem which has a variety of novel features.

The preferred embodiment of the laying device of the present inventionhas the advantage of being light weight, about 270 long tons, comparedto about 600 tons for the pipe handling equipment on the aft deck of theApache pipelaying vessel described above.

Other embodiments of the pipeline laying system of the present inventionemploy continuous track straightening and tensioning assemblies mountedon carriages which are reciprocally and pivotally mounted within thepipe take-off structure.

In summary, the preferred embodiment includes a laying device comprisinga rotatably mounted drum and an attached pipe take-off structure whichis operative for laying out a rigid walled pipeline over a very widerange of water depths of from less than 200 feet to much greater depthseven beyond 7,500 feet.

STRAIGHTENER AND TENSIONER DEVICES

The straightening and tensioning devices can be of two types. The firsttype is a straightening device which is operated independently from thetensioning device. The second type is a combinedstraightening/tensioning device comprising two continuous trackassemblies which are employed on opposite sides of the pipeline in orderto provide both the straightening and the tensioning functions. Thesecond type involves the use of a new straightening/tensioning devicewhich is capable of imparting controlled curvature to the rigid walledpipeline and is also capable of providing longitudinal tension force.The advantage of this second type of straightening device is that onlytwo such assemblies are required for both of the straightening andtensioning functions whereas in the first type four or five separatetrack assemblies are usually required for the layout of a rigid walledpipeline.

The pipeline laying device is mounted on the vessel via a carriage whichis capable of level winding transversely across the vessel deck toprovide for controlled spooling and unspooling of the pipeline onto andoff one of a plurality of storage reels. The storage reels are fittedwith hydraulic motors for imparting motive power to the reel flanges orrims in order to provide for spooling up of the lines. The hydraulicmotors are also fitted with hydraulic braking systems for controllingtension of the lines during unspooling and to control the rate of linelayout.

The present invention permits a rigid walled pipeline to be laid out onthe bottom of bodies of water in a controlled and straightened manner.The particular pipe handling means selected for a given project dependsupon the depth of water and the project budget available. Othertechnical/economic considerations such as the permissible capitalinvestment, speed of pipeline layout, customer flexibility of designcharacteristics, and the sea state spectrum also enter into theselection process. The specific straightening and tensioning devicesused are determined by various pipe handling means technicalcharacteristics and economic considerations.

Another feature of the present invention is that a dynamicallypositioned vessel can be alternately converted between a single pipelinelaying capability such as described in the above mentioned Springett, etal, Uyeda, et al and Yenzer, et al patents which is embodied in theApache pipelaying ship and the vessel described in the presentapplication. In order to accomplish this alternate use, the mainpipeline reel is maintained in fixed position and the remainder of thepipe handling equipment shown on the aft deck of the vessel in thoseU.S. patents is replaced with the layout system herein described whichincludes one or two auxiliary reels and the pipeline laying devicedescribed herein. Thus, a convertible capability for changing thepipelaying vessel between an intermediate water depth pipelaying vessellike Apache and a wider depth range vessel is also included within thepresent invention.

It is, therefore, an object of the present invention to provide apipelaying system which can lay out from a vessel deck a straightpipeline onto the sea bottom of waters over a depth range of from about200 feet to over 3,000 feet.

Another object is to provide a pipeline layout system for use on avessel in which one or more storage reels are provided for sequentiallyspooling and unspooling of a plurality of rigid walled pipelines.

Another object of the present invention is to provide a layout system inwhich three storage reels are mounted on a vessel deck for sequentiallyspooling and unspooling pipelines of different diameters for layout ontothe sea bottom after passing through a common laying device whichprovides for straightening of the lines.

Yet another object of the present invention is to provide a layoutsystem which is light weight and can be transferred onto pipelayingvessels by exchange of pipe handling equipment existing on such vesselswith the layout system herein described.

Another object is to provide an improved straightener/tensioner devicewhich permits the establishment of selected curvatures for controllingthe straightening process and applying the desired tension formaintaining pipeline profile over a wide range of layout water depths.

Another object is to provide an improved spooling and unspooling methodfor use with the pipeline layout system herein described.

For convenience, the following terms may be employed in the descriptionof this invention:

1. A "turn" is that length of pipe wound through one complete revolutionof the reel.

2. A "wrap" comprises a plurality of turns making up a layer of pipewound on the reel across the full or substantially full width of thereel.

3. "Level winding" refers to the transverse movement of the layingdevice or a storage reel across the deck of the vessel. The "levelwinding means" refers to apparatus for carrying out such movement.

4. "Track straightening or tensioning assemblies" refers to flexibletrack systems having a plurality of pipe support pads mounted thereonand which are designed for either of the two functions of straighteningor tensioning.

5. The term "track straightening/tensioning assemblies" refers totensioning assemblies which are designed to provide both straighteningand tensioning functions in a single pair of such assemblies whenpositioned on opposite sides of the pipeline.

6. "Carriage" refers to the support frame structure which is used tomount the laying device on the vessel and to provide for level windingthereof.

7. "Main reel" refers to a large diameter storage reel which ispermanently mounted within the vessel for spooling and unspooling rigidwalled pipeline.

8. "Operational lines" include rigid walled metal pipelines which can bepreferably coated, plastic walled lines, electrical cables, tensionsupport cables, etc.

9. The notations "s" for starboard, "p" for port, "f" for fore and "a"for aft have been used for convenience in numerals designations.

Other features and advantages of the multi-reel vessel of this inventionwill become apparent from the following drawings and detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a starboard side elevation general arrangement view of apreferred embodiment of the pipelaying vessel;

FIG. 2 is a top plan view of the vessel of FIG. 1;

FIG. 3 is a schematic side elevation cross-section of a first embodimentof the pipe take-off structure of the present invention;

FIG. 4 is an enlarged starboard side elevation of the operational linereels and the pipe take-off drum of the present invention;

FIG. 5 is a top plan view of the enlarged portion of the vessel of FIG.4;

FIG. 6 is a side elevation of the pipe take-off drum;

FIG. 7 is a cross-sectional view through a portion of the pipe take-offdrum of FIG. 6 taken on line 7--7;

FIG. 8 is a schematic side elevation view of the FIG. 3 embodiment ofthe pipe take-off structure showing the straightening and tensioningdevices in greater detail;

FIG. 9 is a cross sectional view taken through the straightening deviceon line 9--9 of FIG. 8;

FIG. 10 is a cross-sectional view taken through the pipe take-offstructure showing the tensioning device of the present invention takenon line 10--10 of FIG. 8;

FIG. 11 is a cross-sectional view of the pipe take-off structure in FIG.8 showing the pipe alignment clamp taken on line 11--11 of FIG. 8;

FIG. 12 is a side elevation view of the pipe take-off drum support framestructure;

FIG. 13 is a front view of the support frame structure of FIG. 12;

FIG. 14 is a top plan view of the support frame structure of FIG. 12;

FIG. 15 is a partial cross-sectional side elevation view of the pipetake-off assembly without the take-off drum of the present invention;

FIG. 16 is a partial cross-sectional view through the hydraulic powerdrive motor by which the pipe take-off structure is rotated to establishdifferent water entry angles for the pipeline array;

FIG. 17 is a side elevation view of the straightener device of the FIG.8 embodiment;

FIG. 18 is a top plan view of the straightener device of FIG. 17 withthe sprocket chain track removed;

FIG. 19 is a cross-sectional view taken on line 19--19 of FIG. 17showing the adjustable idler rollers and the pipeline support padsmounted on the sprocket track;

FIG. 20 is a side elevation view of one of the auxiliary reels and itssupport frame structure when mounted on the vessel deck;

FIG. 21 is a front plan view of the auxiliary reel shown in FIG. 20;

FIG. 22 is a longitudinal side elevation view of the level wind towerassociated with the main reel;

FIG. 23 is a transverse frontward elevation view of the level wind towerassembly associated with the main reel;

FIG. 24 is a side elevation detailed view of one of the track tensionerassemblies of FIGS. 3 and 8;

FIG. 25 is a top plan view of the tensioner assembly of FIG. 24 with thetrack removed;

FIG. 26 is a cross-sectional view of the tensioner device of FIG. 24taken on line 26--26;

FIG. 27 is a schematic side elevation view of a second embodiment of thepipe take-off structure of the present invention showing the internalposition of the straightening/tensioning assemblies;

FIG. 28 is a detailed cross-sectional view of thestraightening/tensioning assemblies shown in FIG. 27 taken on lines28--28;

FIG. 29 is a detailed side elevation view of thestraightening/tensioning assemblies of FIGS. 27 and 28;

FIG. 30 is a schematic side elevation view of a modification of the pipetake-off structure in which straightening rollers are employed; and

FIG. 31 is a schematic side elevation view of a modification of thepipelaying system shown in FIGS. 1-5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The pipelaying vessel 10 of FIGS. 1-5 has a hull 12 which is constructedwith starboard and port main reel support structures 14 and 16 which areelevated above the fore deck 17 and the aft deck 18. These reel supportstructures rotatably support a main reel 20 which is positioned with itsaxis transverse to the vessel longitudinal axis and which is adapted toprovide storage for a series of wraps of rigid walled pipeline which canbe wound in single or multiple line fashion. A detailed disclosure ofthe vessel hull 12 and main reel 20 is set forth in U.S. Pat. No.4,269,540.

A single pipeline 22 is shown being unspooled from the verticallydisposed main reel 20 onto the pipeline laying device or pipe take-offassembly 24 which includes as a main element a pipe take-off drum 26positioned adjacent the stern 28 of vessel 10. The assembly 24 alsoincludes a pipe take-off structure 30 in which a straightening device 32is supported in forceable contact with pipeline 22. A tensioning device34 is also included within the pipe take-off structure 30 for thehandling of the pipeline 22. The structure 30 rests in a stern notch 29when in its vertical 90° position as shown in FIGS. 1 and 2.

A first auxiliary reel 36 is mounted on a reel support frame 38 on theaft deck 18. Also a second auxiliary reel 40 is mounted on a reelsupport frame 42 which is also supported on aft deck 18. Pipelines 44and 46 can be unreeled from auxiliary reels 36 and 40 alternately withthe unreeling of pipeline 22 from main reel 20. Each of these pipelinesare taken, in turn, into the pipeline laying assembly or device 24 atthe top of the take-off drum 26 and are maintained in continuous contactwith the periphery thereof as the direction of movement of each of thesepipelines is changed from horizontal to vertical at the stern end of thepipe take-off drum 26.

The sequential contact between the operational lines 22, 44 and 46 withthe periphery of the pipe take-off drum 26 results in the changing ofthe direction of movement from horizontal to any angular pipe take-offposition at which the take-off structure is set. The pipelines are thenpassed through the straightening means 32 and the tensioning device 34so that each of these lines passes downwardly over the stern 28 whichcan be at nearly a 90° angle as shown in FIG. 1 for deep water layout.

A level wind assembly 48 is provided for aiding the spooling of pipelineonto main reel 20. The level wind feature is not used during unspoolingsince the pipeline is merely passed through this device so as torestrain the lateral movements. An abandonment and recovery (A/R) cablestorage reel 50 is mounted to fore deck 16 for the storage of two cables52 and 54 which are strung under main reel 20 by a fixed cable doublegroove sheave 56 and a series of cable rollers 58 and 60 through a twindrum traction winch 62. The A/R functions of the cables 52 and 54combined with operation of the traction winch 62 are described below.The A/R cable storage reel 50 has two drum portions 78 and 80 for stoingthe two cables 52 and 54 separately.

A control tower 64 is mounted on the starboard reel support structure14.

Pedestal cranes 66 and 68 are provided on starboard and port sides,respectively.

As shown in FIG. 2, starboard and port exhaust stacks 70 and 72 areprovided for the diesel engine(s) used to power vessel 10. As required,lifeboats 74 and 76 are provided on port and starboard decks at midship.

Rotatable mounting bearings 82 and 84 are shown on either side of mainreel 20 in FIG. 2. The main reel 20 has a hub 85 on which the successiveturns of pipeline are wound.

The vessel 10 has fore and aft lateral thrusters 86, 88, 90 and 92positioned below the waterline 94 to provide for the dynamic positioningof vessel 10 during unspooling of the operational lines. Thus vessel 10is capable of dynamically positioning itself.

PIPELINE LAYING DEVICE

FIG. 3 shows, in general, the operation of the straightener device 32which comprises a first track assembly 102 for contacting the pipeline22. The straightener device 32 has idler rollers described below whichcan be adjusted to provide for various curvatures in the pipeline 22.The tensioning device 34 is formed by a second track assembly 104 and athird track assembly 106 which act on opposite sides of the pipeline 22,respectively, in order to provide tension for supporting the pipelineweight which is suspended from the pipe take-off assembly 24.

In order to straighten rigid walled pipeline, force must be exertedagainst three zones of the pipeline. The periphery of the pipe take-offdrum 26 provides a first force zone A, the straightening device 32provides a second force zone B within which the curvature must change,while the fore track assembly 106 of the tensioning device 34 provides athird force zone C. The straightened pipeline 22 is then passeddownwardly through the pipe take-off structure 30 including the pipeclamp 108 and then into the body of water 110. A pipe aligner 112 isalso positioned within the pipe take-off structure 30 in order to changethe position of the rigid wall pipe 22 over relatively small distances.The pipe clamp 108 is placed before the pipe exits the pipe take-offstructure 30 and is used for pipeline abandonment and recoveryoperations.

The entire pipe take-off structure 30 is mounted on a support framestructure 114 which is in turn rotatably mounted on axle 116 of the pipetake-off drum 26. A hydraulic motor 118 is mounted on a support carriage120 and is arranged to provide power to a peripheral welded chain trackon the arcuately curved outside surface of frame structure 114. In thismanner the frame structure 114 and the attached pipe take-off structure30 are rotated relative to the support carriage 120 in order to obtainvarious pipe water entry angles.

The angle shown in FIGS. 1 and 2 is approximately 90° whereas the angleshown in FIG. 3 is approximately 60°. As mentioned above the rotationalmotion of the pipe take-off structure 30 can be varied between about 20°to about 90°. This permits the pipe take-off structure or the pipelayingdevice of the present invention to lay out operational line array inshallow waters of less than 200 feet in depth for which low angles areused or in deeper waters beyond 3,000 feet for which larger angles offrom 60° to 90° are used. The provision of this wide lay out water depthrange for the pipeline 22 is an important feature of the presentinvention.

The pipe take-off assembly 24 includes the stern mounted drum 26, thepipe take-off structure 30, the support frame structure 114 and thesupport carriage 120 with its underlying level wind track assembly. Theassembly 24 functions as the pipeline laying device. The describedtake-off assembly 24 includes the straightening, tensioning and otherpipe handling equipment and functions as the pipeline laying or lay outsystem.

OPERATIONAL LINES

The operational lines 22, 44 and 46 which are laid out individually fromassembly 24 can be a variety of types which provide for a wide range offunctions. All of the lines can be rigid walled steel or metal pipelinesuch as pipeline 22 which is stored on the main reel 20. The other twooperational lines 44 and 46 can be also plastic lines, electricalcables, tension support cables, etc. Some or all of these lines can bethermally insulated. Non-restricting operating examples are that theline 22 can be a 6 inch o.d. rigid walled pipeline; the line 44 can beof 4 inch o.d. rigid walled pipeline; and the line 46 can be either asingle or dual set of electrical lines. Each of these lines can bepassed over the pipe take-off drum 26 and then passed through thestraightening device 32 and tensioning device 34, even though theplastic, electrical, and support lines may not require straightening andhence are passed through without the straightening device being inoperative contact in order to use the layout drum 26.

Another aspect of the operational lines is that these can be lines whichhave an outer sheath formed about a number of smaller lines which arebundled within the sheath. The sheath for such bundles of lines can beeither continuous walled or in the form of a bundle wrapping. The linesin the bundles can be combined with either single lines or other bundledlines to form operational lines arrays stored on the multi-reel vessel10. Examples are that a 3 inch or 4 inch o.d. sheath line can haveapproximately fifteen one-half inch lines within the same bundlingsheath. Electrical control lines can also be bundled within a sheath.

The main reel 20 can accommodate rigid walled pipe of from 2 inches to16 inches o.d. The first auxiliary reel 36 can accommodate from about 2inch to approximately 9 inch o.d. rigid walled pipeline or otheroperational lines such as electrical cables or tension support cables.

The second auxiliary reel 40 can be utilized for about 2 inch to about 5inch o.d. rigid walled pipelines or tension support cables or electricalcables. The diameter range of the rigid walled pipelines which can bestored on and unreeled from the auxiliary reels is a function of the hubdiameters of those reels as specified below.

It is often desirable to utilize the main reel 20 and the firstauxiliary reel 36 for rigid walled pipelines and to utilize the secondauxiliary reel 40 for the storage and subsequent layout of electricallines and tension support cables.

Also show in FIG. 4 is the boom 122 of the pedestal crane 68. Theelevation cable 124 is also shown attached to the top of the crane arm126.

PIPE TAKE-OFF DRUM

FIGS. 6 and 7 show the outer rim 130 and a central hub 132 of the pipetake-off drum 26. The hub is connected to the peripheral rim 130 by aseries of radial spokes 134-156. The connection at the center of the hubis formed by a central cylinder 158 which is mounted on a rotatable axle116. A series of starboard hub gussets 162-184 are integrally connectedto the cylinder 158 and to a starboard flange ring 186. A similar seriesof port side construction gussets are connected to cylinder 158 and to aport side flange ring 188 as illustrated by port gussets 190 and 192 inFIG. 7.

The spokes are connected to the rim structure 130 by a series ofstarboard peripheral gussets 194-216 and by a similar series ofperipheral gussets on the port side as shown by gusset 218 for spoke 136in FIG. 7.

Pipeline supporting means 220 is supported about the periphery of thetake-off drum 26 and is constructed with an annular groove 224 toprovide for continuous frictional contact with the pipeline duringcontact thereof during the layout operation. The supporting means 220 ismounted on a rim 234 which is integrally connected to the ends of thespokes as shown for spoke 136 in FIG. 7. An internal re-enforcement rim236 is spaced below the outer rim 234 and is connected thereto by thestarboard and port peripheral gussets 196 and 218 respectively as shownin FIG. 7.

Starboard and port side rims 238 and 240 are also connected to the outerrim 234 and extend upwardly on either side of the pipeline supportingmeans 220. The groove 224 forms an indented configuration which extendspartially around the outer diameter of the pipeline which is placed inthis groove during the layout operation. The size of the groove can bevaried depending on the particular pipeline requirements of a given job.For this purpose, the support means 220 is constructed in removablearcuate segments in order to accommodate varying diameters ofoperational lines.

Also shown in FIG. 7 are the internal gussets 242 and 244 which arerepresentative of the series of such gussets provided forinterconnecting the inner and outer rims 234 and 236 with the terminalportions of the drum spokes.

The diameter of the pipe take-off drum 26 is chosen so as to lay out thepipeline with residual ovality at lower than the maximum limitsspecified by the international certification organizations. Theseovality limits are not necessary for all offshore construction projectsso that specific pipelines can be laid in some territorial areas withoutobserving such limits.

It has been found satisfactory to size the drum 26 radius with respectto the pipeline diameter. The wall thickness of the pipeline is also ofinterest with respect to the pipe diameter. A satisfactory set ofrelationships for sizing the drum 26 radius is:

    R≧18 D                                              (1)

where R is the drum 26 radius measured to the pipeline center in givenunits; and D is the pipeline outer diameter measured in the same units.A correlated relationship of pipeline diameter to pipeline wallthickness is expressed by:

    D/T<30                                                     (2)

where D is pipeline outer diameter in given units and T is pipeline wallthickness in the same units.

A preferred relationship is:

    D/T<20                                                     (3)

where D and T are as above defined.

STRAIGHTENING AND TENSIONING ASSEMBLIES IN GENERAL

The pipe take-off assembly 24 generally described in FIG. 3 is shownwith greater detail in FIGS. 8-11. The pipe takeoff structure 30 andsupport frame structure 114 are integrally constructed with a top portside radial frame member 250p which extends from its connection with abearing sleeve mounted on the pipe take-off drum axle 116 beyond theperiphery of the drum 26 and an aft beam 252p which is perpendicularlyconnected to that top side frame member at its stern end. Anintermediate frame member 254p is connected to the end of a radial framemember 256p through the arcuate frame member 260p. The frame member 256phas the other end thereof integrally connected to the bearing sleeve257p (FIG. 15) on the drum axle 116. A third radial beam 258p is alsoconnected to the sleeve 257p about drum axle 116 and extends beyond theperiphery of drum 26 in order to form the fore frame section of the pipetake-off structure 30.

The arcuate cradle members 260p and 260s are connected between thestarboard and port radial frame members 250, 256 and 258 and aredesigned to be rotated with these members about the periphery of drum26. The frame members 250p-260p form the port side of the structuralsupport for pipe take-off structure 30. A corresponding starboard set ofstructural members are connected to the above described port side set bytransverse frame members 262, 263, 264, 266, 267, 268, 269, 270, 272,273, 274, 276 and 278 (numbered in clockwise positioning from lowerright) which are interconnected at the framing juncture points betweenthe starboard and port frame members.

Starboard and port sets of parallel structural guides are provided foradjustably mounting straightening device 32 and the two halves oftensioning device 34 within the pipe take-off structure 30. Portstructural guide set 280p has three parallel internal guide frames 282p,283p and 284p which are connected by the aft end thereof to thetransverse frame members 272, 273 and 274, respectively. The fore endsof the internal guide frames 282p, 283p and 284p are connected tomatched exterior side frame members illustrated by frame 285p viaspacers illustrated by 286p in FIG. 9. This side frame 285p is, in turn,connected to arcuate cradle member 260p.

A similar port set of parallel internal guide frames 287p is providedfor the tensioning device 34 by guide members 288p, 289p and 290p whichare connected at the aft end thereof to transverse members 267, 268 and269 and to port and starboard side spacer members as shown by members292p and 292s (FIG. 10) A matching set of internal guide frames 288s,289s and 290s are positioned on the starboard side of the pipe take-offstructure 30 for guiding the aft positioned second track assembly 104which forms part of the tensioning device 34. These internal guides arereinforced by matched exterior side frame members illustrated by frames294p and 294s (FIG. 10) in similar fashion to that described above forthe straightening device 32.

The third track assembly 106 which forms part of the tensioning device34 is similarly set in internal guide frame 296p which is formed byparallel structural members 298p, 299p and 300p which are affixed to theside frame members as shown by and 300p which are affixed to the sideframe members as shown by frame 294s. (FIG. 10) and then to arcuatemember 260p. Side spacer members 302p, s and 304p,s, respectively, areprovided for positioning the middle internal guides 299s,p. A starboardset of structural guide members 298s, 299s and 300s are also providedfor mounting the third track assembly 106. The lower guide frames 300pand 300s are spaced from matched exterior frames by similar spacers.

The straightening device 32 is formed by the first track assembly 102and the hydraulic positioning rams 306p and 306s which are positioned onthe port and starboard sides of the main track carriage 308,respectively. Guide rollers 310p, 311p and 312p are rotatably mounted onthe port side of carriage 308 in a position to contact the internalguide frames 282p, 283p and 284p, respectively. The operation of therams 306p and 306s permit both sliding, S₁, and pivotal, S₂, adjustmentof the first track assembly 102 with respect to the upper and lowerpositioned internal guide frames 282p, s and 284p, s. The lowerhydraulic rams 306p and 306s are pivotally connected by fixed ears 314pand 314s to the aft structural transverse member 273. The hydraulic rampiston rods 316p and 316s are also pivotally connected to the port andstarboard sides of the main carriage 308, respectively, via connections317p and 317s (FIG. 9). Sprocket gear wheels sets 318 and 320 arerotatably mounted in bearings on the top and bottom ends of the maincarriage 308 for supporting a corresponding series of track mechanisms322. Adjustable sprocket idler gear sets 324 and 326 are mounted on theaft side of the main carriage 308 on hydraulic cylinder mounts 325 and327, respectively, for providing additional support for the series oftrack mechanisms 322.

The track mechanism 322 is further described below with reference toFIGS. 9 and 17-19. The first track assembly 102 has an idler assemblycarriage generally designated as 328 which provides a series of idlerroller sets which force the flexible chain track 322 into contact withthe pipeline 22. Further details of the operation of the first trackassembly 102 and the idler roller assembly 328 are set forth below.Screw jack adjusters 329 are provided for manually changing the positionof the rollers to establish selected curvatures. The mounting andoperation of the straightener device 32 permits various curvatures to beformed by the flexible track 322.

The second track assembly 104 which, in part, comprises the tensionerdevice 34 is positioned by hydraulic rams 330p and 330s which arepositioned on either side of the second track assembly main carriagebase 332. Port side guide rollers 334p, 335p and 336p are rotatablymounted on the port side of the main carriage member 332 (shown in FIGS.24 and 25) for engaging the parallel structural guide members 288p, 289pand 290p, respectively. This type of screw jack is sometimes referred asa jacuator. Starboard guide rollers 334s, 335s and 336s are provided forthe starboard side of the main carriage 332 and for contacting thecorresponding structural guides 288s, 289s and 290s.

A similar set of shorter rams 338p and 338s are provided for the thirdtrack assembly 106 which forms the second part of the tensioning device34. The third track assembly is positioned by these rams within the portand starboard structural guide sets 298s, p 299s, p and 300s, p. Guiderollers 340p, 341p and 342p are positioned on the port side of maincarriage member 344 for providing rolling contact along the port guideframe sets 298p, 299p, and 300p.

Hydraulic motors 346 and 348 are provided for the starboard side oftrack assembly 104 in order to drive the flexible chain track 349 whichis mounted on corresponding sets of driven sprocket gears 350 and 351,respectively, shown in FIG. 25. An idler roller assembly 352 is providedfor the tracks 349 and corresponds in relative position to the idlerassembly 328 for the first track assembly 102. FIG. 10 showsrepresentative adjustment cylinders 353s, p which permit variation inapplied force for the idler roller assembly 352. The opposingoperational lines support pad pairs 354a and f are positioned on eitherside of the pipeline 22. Also configured backup rollers 355a and 355fare shown in phantom as used for assemblies 104 and 106.

Similar guides and idler assemblies are provided for the third trackassembly 106. The detailed description of track assemblies 104 and 106is set forth in connection with FIGS. 24-26, below.

An alternate track assembly for the third track assembly 106 is to mountthe hydraulic rams 338p and 338s between the main carriages 332 and 344of the two opposing track assemblies 104 and 106. It is necessary toprovide for imposition of different forces on the operational line arrayby these two opposed track assemblies since track assembly 106 providesthe third force zone of a three zone straightening system as describedwith respect to FIG. 3. The force exerted at the third zone forstraightening is of course separate from the tensioning force which isexerted through any alternate hydraulic rams connected between the maincarriages. In this alternative the hydraulic rams 330s and 330p wouldprovide the straightening force exerted by assembly 106.

Other important features of the pipe take-off structure 30 are thepivotally connected floor panels 356 and 358 of the working platformwhich can be adjusted with respect to various angular operatingpositions of the cradle members 260s, p. This working platform enablesvarious important pipe handling functions to be performed within thepipe take-off structure. Also a lower winch housing 360 and anabandonment/recovery (A/R) cable winch 362 are attached on diagonal aftbeams 363p, s which are mounted at the bottom ends thereof on base sidebeams 365p, s. Fore positioned diagonal beams 366p, s are also mountedon the base side beams 365p, s.

A pipe aligner clamp 367 is also positioned within the pipeline opening368 which is formed by an open box structure 369 constructed of I-beams369a, f, p, s (FIG. 11). A pipe aligner double clamp set 370 ispivotally attached by connection 372s and 372p to the interior of theframe members constituting the pipe take-off structure 30. The pipealigner clamp set has two hydraulic rams 374 and 376 which arecoordinated to operate a clamp about the rigid walled pipelines in orderto align the same. The two hydraulic rams can be utilized forpositioning and aligning the rigid walled pipes or other operationallines within the opening 368.

PIPE TAKE-OFF SUPPORT CARRIAGE

The support carriage 120 of FIGS. 12-14 has a starboard baselongitudinal beam 390 which is connected to fore and aft transversebeams 392 and 394. The port side of these structural beams is connectedto a port frame member 396 to complete a generally rectangular framebase construction. Additional intermediate base frame members 398 and400 (FIG. 13) are provided parallel to the starboard and port beams 390and 396. Upon this base frame a starboard bearing housing 402 issupported by a series of six structural members 404, 406, 408, 410, 412and 414 secured at the bottom ends thereof to the above-described framebase members. The bearing housing 402 provides rotational support forthe starboard side of axle 116 of the pipe take-off drum 26. A similarport side bearing housing 415 is supported by the six port sidestructural members 416-426 which are secured at the lower ends thereofto the frame members above described.

The bearing housings 402 and 415 are separated by a distance sufficientto accommodate the drum 26 and the support frame structure 114. Ifdesired these bearing housings may be in the form of cradles from whichthe drum 26 can be removed for spooling of pipeline. A gusset frame 426is also positioned between the bearing collars 402 and 415 at the foreend of carriage 120 and contains two hydraulically operated locking pins428 and 430 for engaging openings in the periphery of the cradle members260p and 260s in order to secure the same against rotation when mountedbetween the bearing housings. This gusset frame 426 is constructed ofvertical members 427p and 427s and diagonals 429p and 429s. The verticallengths of the structural supporting members 404-414 and 416-426 aresufficient to accommodate the pipe take-off drum 26.

Also provided on carriage 120 are a series of reinforcement gussets 432,434, 438 and 440 as shown immediately under bearing collar 402. Asimilar set of reinforcement gussets denoted as 442 are provided for theport bearing collar 415.

Carriage 120 is mounted for transverse level winding movement of thesupport frame by roller caster sets 444 and 446 which are positioned onthe fore structural member 392. A similar set of roller casters 448 and450 is connected to the aft base structural member 394.

Additional reinforcing base frame members 452, 454 and 456 are providedas shown in FIG. 14 in order to provide additional rigidity for the baseframe. Also a cross beam reinforcement assembly 458 is provided withinthe gusset bracket 426. Openings 459s and 459p are provided in diagonalsupports 429s and 429p for accommodation of hydraulic motor drive gearsas described for FIG. 16 below for operational rotation of the supportframe structure 114.

The pipe take-off structure 30 and its associated cradle support framestructure 114 of the pipe take-off assembly 24 are shown in FIG. 15 withdrum 26 removed. The resulting view is in the nature of across-sectional elevation taken on line 15--15 as shown in FIG. 5. Theconfiguration of the frame members of the take-off structure 30 asattached to the arcuate cradle frames 260s, p is shown by this FIG. 15.Structure 30 houses the straightening device 32 and the tensioningdevice 34 as described with respect to FIG. 8 above.

Frame members within this take-off structure 30 can be extensions of thespoke members 250p, 256p and 259p which are connected by their radialinnermost ends to the bearing sleeve 257p which is rotatably mounted onaxle 116. A radial spoke member 462p is integrally affixed to bearingsleeve 257p on the opposite side from its connection with frame spokemember 256p. The radial outer end of spoke member 462p is connected tothe upper fore end of arcuate frame member 260p. In a like fashion spokeframe member 250p forms an integral connection with the arcuate framemember 260p on its radial outermost end. Additional frame spoke members466p, 468p and 470p are provided between the bearing sleeve 257p and thearcuate frame member 260p. A sprocket chain track 472p is affixed to theperipheral rim 474p of cradle frame member 260p.

The hydraulic motor 118 is affixed to the support carriage 120 and isfitted with a drive sprocket gear (FIG. 16) which interfits with thesprocket chain 472s in order to rotate the frame structure 114 about theaxle 116. The frame structure 114 and the attached pipe take-offstructure 30 are thus rotated about axle 116 which is supported by thesupport carriage 120 and the brace members mounted on the starboard andport sides thereof as described with respect to FIGS. 12-14 above. Thusthe support frame structure 114 fits within the space between thebearing collars 402 and 415 in FIGS. 13 and 14 on either side of thedrum 26. The port side support braces 416, 426 and 424 of the supportcarriage 120 are shown in phantom lines.

LEVEL WIND OPERATION OF PIPE TAKE-OFF ASSEMBLY

The support carriage 120 is mounted on transverse support beams 476 and478 which are affixed to the main deck 18 of vessel 10. These are "T"cross-section beams. The roller supports 444 and 448 are positionedunder the carriage 120 and are designed to fit under the top side edgesof the "T" configuration of these support beams in order to permittransverse movement of carriage 120 together with the supported pipetake-off structure 30 and the frame structure 114. The configuration ofthe roller brackets is such that rollers are disposed both on the topsurface and below the top portion of the "T" support beam whereby thepipe take-off assembly will not be rolled or pitched off from thesupport beams 476 and 478 in heavy seas.

Also shown is the fore gusset frame 426 within which is mounted thehydraulic cylinder pin 428 which is designed for entry into openings onthe starboard rim 474s of the cradle member 260s in order to preventrotation of the same from a given fixed working position. A matchingcylinder pin 430 is provided for entering openings in the port cradleframe 260p.

Also shown in FIG. 15 are the guide frames 282p, 283p and 284p whichprovide tracks for the straightener device 32. The intermediate guideframes 283p and 283s are connected by spacers to exterior frames shownas 285p and 285s in FIG. 9. These exterior frames serve to transmitforce from the cross brace 273 forward to the arcuate frame members 260pand 260s when the hydraulic rams 306p and 306s are exerting force on themain carriage 308 of the straightener device 32.

In similar fashion exterior frame 480p and an intermediate exteriorframe 482p are associated with structural guide set 287p. Theintermediate frame pair 482p and s provide for the transmission of forceexerted by hydraulic rams 330p and 330s to arcuate cradle members 260pand 260s.

Also shown in FIG. 15 are a series of plating panels 484p, 486p, 490pand 492p which are successively forward positioned up to a triangularpanel shape member 494p, which is located in the fore position of thepipe take-off structure 30. A series of openings 496 are provided atlocations along the edges of the panel members in order to provideinterior lighting for the pipe take-off structure 30 which is of coursealso lit by known marine lighting devices.

An entry port 498p is provided as shown in mounting panel 500p. Thisport is used for gaining access to the work floor area 357 via a stairset mounted on carriage 120 (not shown). The pivotal working platforms356 and 358 are shown in their horizontal down positions in FIG. 15. Thesubfloor base frame 365 is shown spaced below the support floor frame364p and the interconnected diagonal braces 363p and 366p.

PIPE TAKE-OFF STRUCTURE ROTATION

The supporting frame structure 114 of the pipe take-off assembly 24 isrotated into various angular positions by hydraulic motor 118 as shownin FIGS. 15 and 16. A sprocket chain gear 506 interfits with thesprocket chain 472s which is in turn mounted on cradle rim 474s. In thepreferred embodiment described herein, only a single hydraulic motor 118is employed. If desired this hydraulic motor shown in the starboardposition with respect to the frame structure 114 can be balanced by asimilar hydraulic motor also mounted on carriage 120 on the port sidethereof. In this event a second sprocket chain is also utilized on theport edge of the rim 474p.

As shown in FIG. 16 the sprocket gear 506 is fitted with a mountingshaft 508 which is integrally attached within gusset frame member 429sof the gusset frame 426. A bushing 510 provides for rotation of sprocketgear 506 about the mounting shaft 508.

The sprocket mounting adapter 512 of hydraulic motor 118 is designed torotate within the stationary base 514 to thereby transmit rotationalforce to the sprocket gear 506 which is interconnected thereto by aseries of bolts shown as 516 and 518. The hydraulic motor front bracket520 is integrally affixed to a pump base 522 which is in turn integrallyconnected to the carriage frame 120. A usable hydraulic motor 118 is aHagglunds Series 80, Model No. 8385.

The angular rotation of the frame structure 114 about axle 116 in turncontrols the position of the operational lines exit port with respect tothe stern 28 of vessel 10. This angular positioning controls the waterentry angle of the pipeline 22. Higher entry angles up to 90 degrees areused for deep water layouts. The hydraulic cylinder pins 428 and 430secure the various set positions.

STRAIGHTENING AND TENSIONING DEVICES IN DETAIL

The straightening device 32 shown and described in reference to FIG. 8can be constructed with the track assembly 102 arranged in one ofseveral configurations. As shown in FIG. 8, the track tensioner idlersprocket gears 324 and 326 can be supported on adjustment mechanisms 325and 327 as shown for the track 322. It is also possible to provide thetension in track 322 by other slightly modified mechanicalconfigurations as described below with respect to FIGS. 17, 18 and 19.

The track 322 can be arranged with pipeline support pads mounted on asprocket chain so that the pipeline is contacted at a given position bya single support pad.

The track assembly which first contacts the pipeline 22 after it passesover the pipe take-off drum 26 should be capable of conforming to andmaintaining an adjustable curvature in order to provide a straighteningfunction for various sizes of rigid wall pipelines.

A preferred configuration of a straightener/tensioner track assemblywhich can be used for both a straightening assembly 102 and, with somemodification to provide for adequate hydraulic power, also forassemblies 104 and 106 is shown in FIGS. 17-19. In this configurationthe sprocket chain tensioner sprocket gears 324 and 326 are mounted byfixed brackets 530 and 532. The desired tension is then exerted on thetrack set 322 by the powered sprocket gears 318 and 320 which areintegrally mounted on axles 534 and 536, respectively, on either end ofthe assembly 102. Axle 534 is mounted in a bearing housing 538 on thestarboard side and in a bearing housing 540 on the port side. Thesebearing housings 538 and 540 are adjustable linearly away from thesupport carriage base 308 by means of hydraulic cylinders 542 and 543,respectively. The bearing housings 538 and 540 are slidably mounted infixed "C" brackets 544 and 546, respectively. Identical bearing housings548 and 550 are provided on the opposite end of the main housing 328 forrotatably mounting axle 536 and these are slidably adjusted by hydrauliccylinders 552 and 554, respectively, within the "C" brackets 556 and558.

The "C" brackets are slidably mounted on extensions 560, 562, 564 and566 of the starboard side plate 568s and the port side plate 568p.Reinforcement studs 570, 572, 574 and 576 are also provided for mountingthe "C" brackets.

The operation of the hydraulic cylinders 542, 543, 552 and 554 permittensioning of the sprocket chain track assembly 322 about the main trackcarriage 308. This frame consists of sides 578 and 580 which are joinedto the starboard and port side walls 568s and 568p in order to completea box frame structure. Starboard and port side mounting brackets 582sand 582p are also attached to the lateral sides of the main trackcarriage 308.

Guide roller assemblies 310s, 311s and 312s are shown attached to themounting bracket 582s. Similar guide roller assemblies 310p, 311p and312p are mounted on the port side bracket 582p. Guide roller assembly310s contacts the frame guide member 282s which can be seen in FIG. 9.Similarly roller guide assembly 311s contacts frame guide 283s androller guide 312s contacts frame guide member 284s. The port side rollerassemblies 310p, 311p and 312p contact the corresponding port side frameguide members 282p, 283p and 284p as shown in FIG. 8. Thus, movement ofthe track assembly 102 toward and away from the pipeline 22 is providedby operation of the hydraulic rams 306s and 306p. The piston rodconnection mounts for the hydraulic rams are denoted as 317s and 317pand are formed in the side walls 578s and 578p and also in the mountingbrackets 582s and 582p in a centrally disposed location close to thepipeline contacting position.

The use of only two guideroller assemblies on either side of the trackassembly 102 which are spaced from the force plane in which thehydraulic rams 306s and 306p function permits a slight rocking motion ofthe assembly as required to adjust to various pipeline diameters andarray configurations. This rocking motion S₂ is in addition to theprimary sliding, linear movement S₁ of the track assembly 102 due tooperation of the hydraulic rams 306s and 306p. These motions are shownby the double headed arrows in FIG. 8.

As shown in FIGS. 18 and 19 the main sprocket wheels or gears arepositioned at either end of the track assembly 102. This pair ofsprocket gears supports a sprocket chain 584 as shown in FIGS. 17 and19. The sprocket chain 584 when placed about the track assembly 102 thencontacts the sprocket gears 318 and 320 (as well as idler sprocket gears324 and 326 on the stern side when mounted as shown in FIG. 8). The sideof the track assembly 102 facing the pipeline contains a series of ninecurvature idler rollers 586 which are slidably mounted within the boxframe of the main carriage 308. The mounting arrangement for thecurvature idler roller set 586 is provided by placing partition walls588 and 590 parallel to the other walls 568s and 568p within the boxframe. The curvature idler roller set 586 is then slidably mountedwithin the box frame.

FIG. 19 shows one of the curvature rollers on a mounting frame 592 whichis slidably mounted between the partition walls 588 and 590. Themounting frame 592 is connected to an adjustment screw 594 which is inturn controlled by a jactuator 596 which can be adjusted through a sideport 598 in side plate 568s and a port 600 in partition wall 588 inorder to move the carriage 592 relative to the main carriage housingwalls. These walls 568s, 588, 590 and 568p together with the spacerwalls 602 and 604 form the curvatured idlers support assembly.

Each of the idlers in the idler roller set 586 is similarly providedwith an adjustment screw and a jactuator for adjusting the position ofthe idlers in order to contact the pipeline with the pipeline supportpad 606 as shown in FIG. 19. This individual adjustability feature foreach idler roller in the roller set 586 then permits various selectedcurvatures to be established for each of the operational lines in thearray. The set of jactuators 608 which adjust the position of the set ofcurvature idlers 586 can be adjusted from either side of the trackassembly 102. Ports 610 and 612 are provided in side wall 568p inpartition wall 590, respectively, for that purpose. Jactuator operators614 and 616 as seen in FIG. 19 permit adjustment of jack screw 594. Thehydraulic piston rods 316s and 316p are seen connected to the starboardand port sides of the assembly 102 at connections 317s and 317p,respectively.

STRAIGHTENER TENSIONER DEVICES VARIABILITY

A number of degrees of flexibility are provided by the straightener andtensioner devices 102 and 104, respectively, as described herein withrespect to FIGS. 8-10 and 17-19. The more significant of these are asfollows:

1. The idler roller assembly 586 with its individually adjustablecurvature idlers permits incremental changes in curvature of thepipeline 22. As the pipeline comes off the drum 26 these idler rollersand their associated tracks establish the adjusted curvature needed forcontrolled straightening.

2. The mounting of the track assembly 102 on the parallel guide frames282s and 282p and on 284s and 284p for reciprocation by the hydraulicrams 306s and 306p via the roller pairs 310 and 312 mounted on eitherside of the track assembly 102 provides for both a reciprocal movementdenoted by the double headed arrow S₁ and a slight rocking arcuatemotion denoted by double headed arrow S₂ (FIG. 8).

3. The intermediate roller pair 311p and 311s provide additional slidingcontact within tne pipe take-off assembly 30.

4. The track mechanism 322 can be easily removed by retracting thetensioning hydraulic cylinders 542 and 543 as well as the opposingcylinders 552 and 554 in order to remove the tension from the sprocketchain. This chain may then be removed by removal of one or more of thelinking pins while the main carriage 308 remains in its position withinthe pipe take-off structure 30. In this manner the pipe support padsillustrated by the single pad 606 can be exchanged and/or replaced inorder to accommodate pipelines having different diameters.

5. It is also possible to operate the track assembly 102 with varyingdegrees of curvature for contacting the pipelines by reason of theadjustments provided by the jactuator set 608. This is particularlysignificant with respect to use of two of the straightener assembly 102as the track assemblies for tensioning device 34.

The arrangement of the pipe straightener device 32 with respect to drum26 provides the two pipe straightening force zones A and B as describedwith respect to FIG. 3. The placement of the track assembly 106 belowthe two force zones A and B permits the use of track assembly 106 toprovide a third force zone C. In this manner the drum contributes zone Aand the need for a fourth track assembly in order to provide one of theforce zones is eliminated thus reducing the capital cost of the pipetake-off assembly 24.

Another advantage of the straightener device 32 and the tensioningdevice 34 in the locations shown in FIGS. 3 and 8 with respect to drum26 is that only a few mechanical devices are required for providing bothpipe straightening and tensioning. This configuration permits thecontacting of the pipeline 22 by the straightening device 32 prior toengagement of the array by the tensioning device 34. This permits theproper functioning of the tensioner device 34 which must be operated inorder to have the same force exerted on both sides of the pipeline 22.When the zone B primary pipeline straightening force is exerted by oneof the two tensioning devices this equalization of tensioning force ismore difficult to control since zone B balances the zone A and B forces.Therefore, it is preferred and operationally significant to have thepipeline contacted by the straightener device 32 as it is unspooled andtaken off the pipe take-off drum 26 prior to contact with the tensionerdevice 34.

AUXILIARY REEL STRUCTURE

Auxiliary reel 36 can have a fixed position near the longitudinalcenterline of the vessel 10. It can be supported by transversely deckmounted base I-beams 620 and 622 as shown in FIG. 20. A level wind trackassembly is not required since the pipe take-off assembly is mounted fortransverse level winding. The operational line 44 is not required to betaken off the reel 36 along a longitudinal plane since a small fleetangle can be tolerated. The reel is supported on the base beams 620 and622 by the reel support structure 38 which is formed by two A-frames 624and 626 which are described in detail below.

The second auxiliary reel 40 is similarly mounted on main deck 18 by twosupport frames which are similar, but of slightly less reinforcedconstruction than the A-frames 624 and 626.

Auxiliary reel 36 and the associated frame supports 620 and 622 areillustrated in FIGS. 20-21. The reel 36 is constructed with a centralhub 628 and an outer storage drum 630 on which a single woundoperational line or pipeline is reeled for storage. The outer reelflanges are illustrated in FIG. 21 by the starboard side flange 632which has a continuous sprocket chain 634 affixed to the peripherythereof. A series of spoke frames 636-664 are provided for connectingthe inner hub 628, the storage drum 630 and the side rim 632 in order toform the reel 36. As shown, circumferentially arranged reinforcingmembers 666-696 are connected at intermediate positions between thecentral hub 628 and the side rim 632.

As shown in FIG. 21, the side rim 632 is spaced from the correspondingport side rim 698 by the width of the storage drum 630. The reel 36 ismounted on an axle 700 which is provided with axle bearing housings 702sand 702p. The starboard and port axle bearing housings are, in turn,mounted on the reel frame supports 620 and 622, respectively. Thestarboard reel frame 624 is formed by triangularly arranged framemembers 704s, 706s and 708s, the fore and aft of which are inclined fromthe frame base 710 upwardly toward a pedetal plate 712s which providesthe foundation for the axle bearing housings 702s as shown in FIG. 21.This exterior set of slanted frame members 704s, 706s and 708s arematched by an interior set of inner frame members 714s, 716s and 718swhich are positioned in the vertical plane. All of these reel supportframe members are connected at their bottom ends to the reel supportframe base 710. In order to reinforce the starboard support reel frame624, side gussets 720s and 722s, as well as end gussets 724s and 726sare provided within frame 624 immediately below the bearing housing702s. Similar gussets are provided on the port side.

By projection to FIG. 21 it can be understood that the same reel supportframe construction is employed on the port side of reel 36 by means ofsupport frames 704p, 706p and 708p on the exterior of the support frameand elements 714p, 716p and 718p on the interior position. The port sideframe supports a bearing pedestal 712p.

The reel support frame base 710 is in a flat frame configuration withstarboard and port I-beams 728s and 728p disposed on the outer sideswith reinforcing I-beam sets 730s and 730p spaced to the interiorthereof. These I-beams are connected on the fore end by transverse foreI-beam 732 and aft transverse I-beam 734. Additional reinforcing framepipes can be provided in a transverse positioning in order tointerconnect the longitudinally aligned I-beam sets 728s,p and 730s,p.Diagonal reinforcing pipe frames can also be provided in the same baseplane.

Support frames 624 and 626 have additional reinforcing pipes 736s, 738s,740s and 742s positioned at an intermediate height as shown in FIG. 20.Similar intermediate reinforcing pipes are provided for the port supportframe 626.

Internal reinforcement members are provided for the drum 630 as shown inFIG. 21. Cross support beams illustrated by beam 746 are provided foreach pair of frame spokes which are illustrated by the starboard spokeset 636-664. For each of the cross beams 746 a set of three reinforcingstruts 748, 750 and 752 are provided for connecting the drum 630 withthe central axle 700. Internal reinforcing corner blocks 754 and 756 arealso provided in this construction. Opposite each such 3-strutreinforcement brace configurations in the reel 36 is a two memberreinforcement brace consisting of struts 758 and 760 which are connectedat their outer ends to a cross frame member 762 via a connector block764 and at their inner ends to the axle 700. This internal reinforcementprovides for a reel 36 having sufficient bearing strength to support aload of spooled rigid walled pipeline as an operational line.

A similar internal reinforcement arrangement is preferably provided forthe auxiliary reel 40.

FIGS. 20 and 21 illustrate the use of four hydraulic motors 766s and766p on the fore side of the reel 36 and 768s and 768p on the aft side.These hydraulic motors are arranged to contact to sprocket chains 634and 771 which are positioned on the side rims of the flanges 632 and698. These hydraulic cylinders and their associated sprocket chainsoperate similarly to hydraulic motors and sprocket chains which areprovided for the same purpose on the reel 40.

The hydraulic motors 766s,p and 768s,p are mounted on the base frame 710of the reel support frame 624 and 626.

Upon operation of the hydraulic motors 766s,p and 768 s,p in order torotate the reel 36 in a clockwise direction as shown in FIG. 20, apipeline can be reeled on the storage drum 630. During the spoolingoperation the pipeline 44 is run through the pipeline take-off assembly24. During the unspooling operation the hydraulic systems which providepower to the four hydraulic motors can be operated in order to provide abraking force for the reel 36 in order to provide additional tension forthe pipeline 44 which is being paid out over the drum 26 for layout. Thesame type of braking system can be employed for the hydraulic motors ofthe other auxiliary reel 40.

Base frame 710 is connected to the transversely positioned I-beams 620and 622 via four connector clamp assemblies 770s, p and 772s,p.

MAIN REEL LEVEL WIND ASSEMBLY

The main reel level wind assembly 48 is founded on the reel supportstructures 14 and 16 immediately aft of the main reel 20. As shown inFIG. 22 the mounting bases 776s and 776p are positioned at the aft edgeof main reel 20. The assembly towers 778s and 778p have reduced diameterextension portions 780s and 780p about which are mounted a supportcarriage 782. This carriage is supported between the tower extensions780s and 780p by a lower transverse frame structure 784 and an upperframe 786. The lower transverse frame 784 has tower extension followersleeves 788s and 788p which permit vertical sliding movement along thetower extensions 780p and 780s. As seen in FIG. 23, in phantom, the reel20 is positioned between the two towers 778s and 778p.

The level wind roller carriage 790 contains a set of hourglass starboardpipeline rollers 792s and 794s which are mounted in a box frame 796.This frame is, in turn, mounted between the frame member 784 andtransverse top frame 786. A walkway structure 798 is provided below thelower transverse frame structure 784 to permit personnel to adjust thepipeline roller pairs 792 and 794.

The lower transverse frame structure 784 is also connected to the upperframe structure 786 by side supports 795s and 795p. The upper transverseframe member 786 is provided with tower extension coupling rings 800sand 800p to enable sliding movement therealong.

The pipeline roller carriage 790 is mounted for transverse movementbetween the frame structures 784 and 786 to enable level winding of thecariage in a transverse direction between the towers as denoted by thedouble headed arrow 802. The level wind arrangement power means employedis a centrally mounted hydraulic motor 804 which operates a jactuatorand screw assembly (not shown) which is similar in operation to thatshown in FIGS. 20-21 for reel 40.

Adjustment screws are provided for the four pipeline hourglass rollers792s,p and 794s,p in order to accommodate varying pipeline diameters.Also fore and aft mounted pipeline support rollers 806 and 808 areprovided for additional support for the pipeline as unreeled from mainreel 20. The main reel level wind assembly is similar to the level windassembly 560 of U.S. Pat. No. 4,269,540.

In operation, the power winches 810s and 810p located at the mountingbases 776s and 776p of the towers are utilized for raising and loweringthe roller carriage 790 along its supporting transverse structures 784and 786. The exterior mounted winch cables 812s and 812p extend from thewinches 810s and 810p upwardly along the outside of the columns andextensions thereto over the double pulley sets 814s and 814p wherebythey are attached to the upper frame slide rings 800s and 800p atconnections 816s and 816p.

The operation of the winches 810s and 810p permit the entire pipelineroller assembly 790 and its associated transverse structural frames 784and 786 to be moved vertically along the tower extensions 780s and 780pas shown by the phantom lines in FIGS. 23 to accommodate various wrapsof the pipeline as it is spooled.

The main reel level wind mechanism 48 is operated positively throughhydraulic motor 804 and power winches 810s and 810p during the spoolingoperation in order to place the successive wraps on the main reel. Thehydraulic motor 804 is not used during unspooling since the pipetake-off assembly 24 is level wound transversely across stern deck 28 toassure correct alignment as the pipeline is unspooled. The pipeline ismerely fed through the hour-glass rollers pairs 792 and 794 foradditional support against wave motion.

The winches 810s and 810p are used to lower the roller carriage andframes 784 and 786 in a controlled manner as the successive pipelinewraps are unspooled so that the weight of the two frames is not on thepipeline(s).

The level winding provided for the pipeline take-off assembly 24 neednot be across the full width of the main reel since a permissible fleetangle of about 1.5° can be accommodated on both the port and starboardsides by the assembly 24. The fleet angle is measured between verticalconstruction planes positioned parallel to the vessel longitudinal axisand the centerline of a given operation line being unspooled.

TENSIONER TRACK ASSEMBLY

The tensioner track assembly 104 of FIGS. 24-26 was briefly described inrelation to FIGS. 8 and 10. The main carriage 332 consists primarily ofa front plate 820 and a rear plate 822 (FIG. 26) which are spaced byinternal starboard wall 824s and internal port wall 824p. Starboard andport mounting side brackets 826s and 826p are positioned in a centrallocation as shown in FIGS. 24 and 25. These brackets consist of innerand outer space inverted "U" shaped members which are connected toextensions of the spaced plates 820 and 822.

FIG. 25 shows the mounting extensions 827s and 827p for mountingassociated bearing housings 828s and 828p. A driven axle 830 isrotatably mounted within these bearing housings and hydraulic motors 346and 832 are provided on either end thereof in order to supply rotationalpower. Reaction levers 834s and 834p are fixed to extensions 836s and836p of the mounting brackets 826s and 826p. Similar mounting extensions838s and 838p are provided for mounting bearing housings 840s and 840pfor providing rotational support for a driven axle 842 which is in turnrotated by hydraulic motors 348 and 844 which have reaction levers 846sand 846p similarly fixed to extensions of the mounting brackets oneither side.

The hydraulic motors 346, 348, 832 and 844 are thus arranged to rotatethe driven axles 830 and 842 in order to rotate the sprocket drive gearsets 350 and 351 about which the flexible sprocket chain set or track349 is positioned. As shown in FIGS. 24-26 a single flexible sprocketchain is provided in order to support a series of transverse mountingback up plates illustrated by plates 848 and 850 in FIG. 26. A set ofpipeline support pads 852 for engaging the pipeline 22 are affixed tothe individual mounting plates as shown in FIG. 26. This arrangement isdistinguishable from that shown in FIG. 28 below in that the back upplates are not required to extend transversely across the width of thecarriage 332. The tracks and support pads have been removed from FIG. 25for clarity.

The idler roller assembly 352 is formed by five transversely disposedaxles having two rollers on each axle. The rollers contact the undersideof the flexible sprocket chain set 349. Each of the five axles isindependently mounted on adjustment hydraulic cylinders illustrated bycylinders 353s and 353p in FIG. 26. Each of these hydraulic cylinderscan also bee seen in the FIG. 25 top view.

The side position mounting brackets 826s and 826p are formed withhydraulic ram connection points 854s and 854p through both of theinverted "U" spaced members thereof. Also guide roller assemblies 340s,340p, 341s, 341p, 342s and 342p are provided for sliding contact withframe guide members 288s, 288p, 289s, 289p, 290s and 290p inside ofstructure 30 as described with respect to FIG. 8.

Adjustment in tension of the flexible sprocket chain set 349 can be madeby the individual hydraulic cylinders 353s and 353p and also by theadjustment hydraulic cylinders 856s and 856p which operate to movedriven axle 830 with respect to the main carriage 332. Similaradjustment hydraulic adjustment cylinders 858s and 858p are used formounting the bearing housings 840s and 840p respectively for moving thedriven axle 842 with respect to the main carriage 332. An additionaladjustment hydraulic cylinder 860s and 860p can be provided on eitherside of driven axle 842 in order to provide for minor advancementadjustments in the sprocket chain track 349 during operation.

The tensioner track assembly 104 described with respect to FIGS. 24-26above is usually designed so that each of the adjustment cylindersillustrated by 353s and 353p in FIG. 26 for each of the five idlerroller axles operate at the same hydraulic pressure and therefore aresubject to the same force exertion and position. This action togetherwith the rather short distance from one end of the roller assembly 352to the other in the direction of track travel means that this type oftensioner assembly is not designed for curvature adjustment. Also theadjustment dimensions for movement of the axles with respect to themounting plate 820 is too small to accommodate curvature adjustments ofthe type described with respect to the straightener assembly 102 inFIGS. 17-19 above. For these reasons, the tensioner track assemblies 104and 106 as shown in FIG. 8 are utilized solely for providing tension tothe pipelines as they are sequentially passed through the pipe handlingequipment. These are not usable for straightening since they do notpermit curvature adjustment of the type required for use in the layingdevices described herein.

PIPE TAKE-OFF ASSEMBLY WITH STRAIGHTENER/TENSIONER DEVICE

A preferred form of the present invention with respect to operatingefficiency and capital costs minimization is shown in FIGS. 27-29.

This modification of the straightener/tensioner device has the advantageof permitting the layout of pipelines sequentially from a plurality ofstorage reels at lower than expected capital and operating costs.

In this modification the straightener/tensioner track assembly has thecapability of imparting an adjustable curvature to the pipelines. Thedevice is fitted with hydraulic motors in order to exert tension on thepipeline. Thus, the adjustable curvature established by the idler rollerassembly provides a pipeline straightening function and the use ofhydraulic motors to power the sprocket chain track provides a tensioningfunction. By use of this new type of straightener/tensioner assemblyonly two opposing assemblies are needed to constitute astraightening/tensioning device which can then be positioned within thepipe take-off structure 30. The drum 26 provides the first forceimposition zone A while the racks 1042 and 1044 provide zones B and C asillustrated in FIG. 36. Due to the curvatures which can be establishedin the tracks the latter two zones can be adequately spaced from oneanother.

The pipeline 22 is moved over the pipe take-off drum 26 shown in FIG. 27prior to its entry between the two opposing straightener/tensioner trackassemblies 862 and 864 which constitute the straightening/tensioningdevice 866. The aft mounted assembly 862 which provides for the force Bstraightening zone is approximately 50% longer than assembly 864 in adirection parallel to the pipeline pathway. Each of thestraightening/tensioning assemblies 862 and 864 are slidably mounted onstarboard and port structural guides illustrated by guide members 868pand 870p for assembly 862 and members 872p and 874p for assembly 864.

As set forth with respect to FIG. 8, hydraulic ram pairs 876 and 878 arepivotally connected by upstanding connectors 880s,p and 882s,p in orderto provide adjustment in positioning for the straightening/tensioningassemblies. The engagement of guide rollers on the structural members868p, 870p, 872p and 874p is the same as described with respect to theembodiment illustrated in FIG. 8. Also intermediate structural memberscorresponding to 289s,p of FIG. 15 are used in this modification.

The remaining pipe handling equipment such as the pipe aligner doubleclamp set 370, the pivotal floor panels 356 and 358, the A/R winch 362and pipe clamp 367 are the same as described with respect to FIG. 8 andhence the same numeral designations have been employed.

The tensioning function of the straightening/tensioning device 866requires the use of motive power for the pipeline contacting tracks 884and 886. This traction power is provided by eight hydraulic motors whichare mounted on the two ends of each of the four main axles in thestraightening/tensioning device 866. The starboard set of thesehydraulic motors are shown as 888s, 890s, 892s and 894s in FIG. 27.

FIGS. 28 and 29 illustrate in greater detail thestraightening/tensioning device 866. The two assemblies 862 and 864which comprise device 866 are of identical construction. In view of theidentical construction only a single set of identifying numerals hasbeen employed for the same elements in the two assemblies except thatthe designations "a" for aft and "f" for fore have been used todesignate the operating position of the assembly under description. Theframing members of the pipe take-off structure 30 are the same as thosedescribed in detail with respect to FIG. 8.

STRAIGHTENING/TENSIONING ASSEMBLIES

The straightening/tensioning assemblies 862 and 864 are similar in basicconstruction to the straightening assembly illustrated in detail inFIGS. 17-19 with the important difference that hydraulic motors areprovided for straightening/tensioning assemblies 862 and 864 for drivingthe main axles which are best illustrated in FIG. 18 as 534 and 536. Themotive power for each of the assemblies is provided by the fourhydraulic motors described and illustrated in detail in FIGS. 28 and 29.Reaction levers 896s, 898s, 900s and 902s are provided for connectingthe stationary bases of the hydraulic motors to the assembly starboardand port side mounting brackets 904a and 904f as illustrated in FIG. 29.The connection of these lever arms 896-902 with the assemblies isthrough slot and pin connections 906s, 908s, 910s and 912s,respectively, in order to allow for adjustments in tensioning of thetracks 884 and 886 by the hydraulic pistons 914s, 916s, 918s and 920s.

In operation the relative positions of the two assemblies 862 and 864are adjusted by operation of hydraulic cylinders 876s and 878s which areshown in FIG. 29 in front of the support frames 869p and 873p,respectively. A pipeline 22 can then be passed downwardly by rotation ofthe pipe take-off drum 26 and thence through the device 866. Uponactivation of the hydraulic ram pairs 876 and 878 the two assemblies 862and 864 can be closed on either side of the pipeline so that it ispressed between the opposing line support pads which are mounted on theendless sprocket chain tracks 884 and 886 as shown in FIG. 29. As inFIGS. 17-19 the two straightening/tensioning assemblies are connected atthe port and starboard sides of each of the main carriages 924 and 926by pivotal connections 928s, p and 930s, p, respectively.

As is shown in FIGS. 17-19 guide rollers 932s and 934s are positioned tosupport assembly 862 on the frame tracks 868s and 870s which can be seenin FIG. 29. The central positioned guide roller 936s is positioned incontact with the intermediate structural frame members 869s.Corresponding guide rollers 938s, 940s and 942s are provided on thestarboard side bracket 904f.

The internal structure of each of the assemblies is the same asdescribed with respect to FIGS. 17-19. A series of jactuator adjustmentopenings 944 and 946 are shown in assemblies 862 and 864, respectively.These jactuator adjustments permit the turning of internally mountedjack screws in order to position the multiple roller guidesindependently. As shown in FIG. 29 fourteen (14) roller guide sets areprovided for the aft assembly 862 since it takes up the straighteningforces at zone B. Nine (9) roller guide sets are provided for the foreassembly 864. For a marginally lower cost assembly 862 the lower 5 to 6roller guide sets can be omitted as shown by section M since thepipeline 22 has been sufficiently straightened in the top one-half ofthe assembly. Sight openings 948 and 950 are also provided through thevarious walls of the two assemblies to check on rotation of thejactuator screws therein.

The operation of the straightening/tensioning device 866 permits the twoassemblies 862 and 864 to be opened and closed about the pipeline viathe hydraulic ram pairs 876 and 878 whereas operation of the internalhydraulic cylinder pairs 914, 916, 918 and 920 allow the tension on theendless tracks 884 and 886 to be changed. The track curvature necessaryto impart the straightening function while minimizing the pipelineovality by this novel straightening/tensioning device 866 is establishedby the mechanical adjustment of the individual screw jacks in order toset the guide rollers at the selected straightening positions for thepipeline.

The tensioning function is provided by motive force input through thehydraulic motors 888s,p; 890s,p; 892s,p; and 894s,p which are connectedto the main axles as described above. The input power from these motorspermits the tensioning along the pipeline in an upward direction asshown in FIG. 29 in order to maintain desired operating tension on thepipeline which passes downwardly through the pipe array clamp 367 andthen into the water.

MODIFICATIONS OF PIPELINE LAYING AND VESSEL

In FIG. 30 a modification of the above described pipelaying system andvessel is shown. The straightener and tensioner assemblies of the pipetake-off structure 30 can be replaced by straightener wheels 960, 962and 964 as shown. For certain deep water pipe layouts only a singlewheel 960 needs to be provided since a first straightening force at zoneA on the pipe take-off drum 26 is counteracted by the force exerted bythe wheel 960 at zone B and a third force in the same direction as theforce exerted by the take-off wheel 26 is exerted at zone C by the seafloor.

It may however be desirable to move the area for exertion ofcounteracting force C up to a position within the pipe take-offstructure 30 in which case a second roller 962 is provided. The thirdroller 964 is, in most cases, optional but is useful in handling certainlarge pipeline diameters of about 8 inch o.d. and above. The rollers960, 962 and 964 can preferably be configured hour-glass rollers.

In FIG. 31 a modification is illustrated in which the pipeline 22 isunspooled from the bottom of reel 20. For this purpose a shortened mainreel level wind assembly 970 is provided. Since the height is reducedthe tower extensions 780s, p disclosed above with respect to assembly 48are not required. In other respects the level wind assembly 970 can beas described above. The pipe take-off assembly 24 including the pipelinetake-off drum 26 and the pipe take-off structure 30 are as describedabove.

The modification of underspooling as shown in FIG. 31 has the advantageof reducing the height of the pipeline 22 over its unsupported span fromthe level wind assembly 970 to the pipe take-off assembly 24. This isadvantageous in certain rough sea areas such as in the northern NorthSea. Thus the pipeline laying system and vessel described herein canutilize either overspooling as disclosed for the modificationsillustrated in FIGS. 1-30 as well as underspooling as illustrated anddisclosed with respect to FIG. 31.

The pipelaying system described herein is adapted for laying out singleoperational lines including rigid walled pipelines onto the bottom ofbodies of water varying in depth from about 200 feet to over 3,000 feet.This wide depth range of pipeline layout is accomplished by use of thepipeline laying device which is mounted adjacent the stern of the layingvessel and which is provided with an adjustable positioning pipelinetake-off structure so that a range of water entry angles from about 20°to approximately 90° is possible. The pipeline laying deviceincorporates a pipeline support means which provides simultaneous movingcontact for the operational lines during lay out. The preferred form ofthe pipeline support means is a pipeline take-off drum which is mountedadjacent the stern of the vessel on a support frame structure.

The pipelaying system comprises one or more storage reels 20, 36 and 40from which operational lines including a rigid walled pipeline can besequentially unspooled and laid out on the bottom of the body of waterby passing each of the operational lines, in turn, through the pipelinelaying device. The operational lines can be unspooled from either a topposition or a bottom position from their respective storage reels. Thepipeline laying device 24 incorporates a pipe take-off structure whichis adapted for adjustable positioning in an arcuate direction spacedfrom the periphery of the pipeline support means in order to establish arange of water entry angles. The pipe take-off structure provides forthe placement of pipeline handling means for facilitating pipelineadjustments and connections which are required for commercial pipelinelaying. Pipe handling means which are included in the pipe take-offstructure 30 can be a work platform as in floor area 357, a pipeclamping means and various positional adjusting equipment.

The vessel upon which the pipelaying system is mounted can be adynamically positioned vessel having transverse force propellerthrusters mounted on the hull below the waterline. The pipelaying vessel10 described herein comprises one or more storage reels for operationallines including a rigid walled pipeline as well as the above describedpipelaying device.

The pipeline take-off structure 30 also incorporates a straighteningdevice and a tensioning device. The straightening device can consist ofa pair of straightening assemblies which incorporate adjustment meansfor providing individual adjustability to enable the establishment ofpredetermined curvatures in the facing directions of the assemblies. Thestraightening assemblies are preferably of a form which have continuousmoving tracks with pipeline support pads mounted thereon.

A straightening/tensioning device is described herein which has bothindividual adjustability for included adjustment means to enable theestablishment of predetermined curvatures in the facing direction of thepipeline support track as well as providing for the application oftensioning force longitudinally along the pipeline. This novelstraightening/tensioning device is also contained within the pipelinetake-off structure.

Both the method of unspooling and laying out a pipeline from the abovedescribed pipeline laying system and vessel and the method for spoolingthe operational lines onto the vessel are described and claimed. Also, amethod of converting a single pipeline laying vessel having a mainstorage reel and a pivotal ramp pipe straightening and tensioningassembly to a vessel which has a main storage reel and a pipeline layingdevice of the type described herein is set forth. Additionally, themethod of reconverting the pipeline laying vessel having the systemdescribed herein back to a single pipeline laying vessel having apivotal ramp straightening and tensioning assembly is set forth.

The level wind apparatus or tower 48 shown in FIGS. 1 and 4 isconsidered to be optional since it is used only for spooling of rigidwalled pipeline onto the reel 20 and additional means such as can beplaced in ports are available for conjunctive use with respect to reel20 for spooling rigid walled pipeline onto vessel 10.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What I claim and desire to have secured by Letters Patent of the UnitedStates is:
 1. A pipelaying system adapted for deployment on a vessel foruse in a body of water comprising:at least one reel for storage andlayout out of a rigid walled pipeline; a pipeline laying device adaptedfor being mounted adjacent the stern of said vessel downstream of saidreel in the direction of unspooling; pipeline support means incorporatedin said laying device and defining a turn for said pipeline, saidpipeline support means comprising a single pipe take-off drum formounting on said vessel for rotation about a horizontal drum axis, withthe surface of said drum providing continous contact with said pipelineso that said drum and pipeline move simultaneously at the same angularvelocity around said turn as said drum rotates; a pipe take-offstructure mounted in said laying device and adapted for arcuate movementin spaced relationship about the periphery of said pipe take-off drum topermit adjustment of the water entry angle of the pipeline, with saidpipe take-off structure pivotally mounted on said axis of rotation ofsaid drum so that said drum and said take-off structure move about thesame axis of rotation, and including first straightener means forapplying a force on the pipeline inward toward said drum axis and secondstraightener means for applying a force on the pipeline outward awayfrom said drum axis, with said drum and first and second straightenermeans providing three point straightening to the pipeline as thepipeline leaves said drum; and motive means operably interconnected tosaid reel and adapted to permit control of the rate of layout of saidpipeline.
 2. A pipelaying system according to claim 1, wherein said pipetake-off structure is adapted for arcuate movement about said supportingmeans to establish a range of entry angles of said pipeline into thebody of water of from about 20° to about 90°.
 3. A pipelaying systemaccording to claim 1, wherein said pipe take-off structure is adaptedfor arcuate motion at a predetermined spaced distance from the peripheryof said pipeline supporting means.
 4. A pipelaying system according toclaim 1, wherein said pipe take-off structure includes pipe tensioningmeans as a part of one of said straightener means.
 5. A pipelayingsystem according to claim 1, wherein said pipeline laying device isadapted for transverse motion with respect to the vessel longitudinalaxis.
 6. A pipelaying system according to claim 1, wherein movement ofsaid pipeline support means is dependent upon frictional contact betweensaid pipeline and said pipe take-off drum.
 7. A pipelaying systemaccording to claim 1, comprising at least one auxiliary operational linestorage reel adapted for being operably secured to the deck of a vesselfor unspooling an operational line through said pipeline laying device.8. A pipelaying system according to claim 7, wherein at least twoauxiliary operational lines storage reels are adapted to be operablymounted to the deck of the vessel, and wherein at least one of saidauxiliary storage reels contains a rigid walled pipeline for unspoolingand laying out through said pipeline laying device.
 9. A pipelayingsystem according to claim 8, wherein said auxiliary storage reels areadapted for being mounted on the deck of the vessel between said reelfor storage and layout of a rigid walled pipeline and said pipelinelaying device.
 10. A pipelaying system according to claim 1, whereinsaid pipeline laying device is adapted for receiving said pipeline as itis unspooled from the bottom of said reel.
 11. A pipelaying systemaccording to claim 1, wherein said pipeline laying device is adapted forreceiving said pipeline as it is unspooled from the top of said reel.12. A pipelaying system according to claim 1, including pipelinehandling means supported by said pipe take-off structure and adapted forfacilitating pipeline adjustments and connections.
 13. A pipelayingsystem according to claim 12, wherein said pipe handling means comprisesa work platform.
 14. A pipelaying system according to claim 12, whereinsaid pipe handling means comprises a pipe clamping means.
 15. Apipelaying vessel adapted for use in a body of water comprising:at leastone reel for storage of a rigid walled pipeline rotatably supported in acontiguous position with respect to the deck of said vessel; a pipelinelaying device adapted for being mounted adjacent the stern of saidvessel downstream of said reel in the direction of unspooling; pipelinesupport means incorporated in said laying device and defining a turn forsaid pipeline, said pipeline support means comprising a single pipetake-off drum mounted on said vessel for rotation about an axistranasverse to the longitudinal axis of said vessel with the surface ofsaid drum providing continous contact with said pipeline so that saiddrum and pipeline move simultaneously at the same angular velocityaround said turn as said drum rotates; a pipe take-off structure mountedin said laying device and adapted for arcuate movement in spacedrelationship about the periphery of said take-off drum to permitadjustment of the water entry angle of the pipeline; with said pipetake-off structure pivotally mounted on said axis of rotation of saiddrum so that said drum and said take-off structure move about the sameaxis of rotation, and including first straightener means for applying aforce on the pipeline inward toward said drum axis and secondstraightener means for applying a force on the pipeline outward awayfrom said drum axis, with said drum and first and second straightenermeans providing three point straightening to the pipeline as thepipeline leave said drum; and motive means operably interconnected tosaid reel and adapted to permit control of the rate of lay out of saidpipeline.
 16. A pipelaying vessel according to claim 15, whereintransverse force propeller thrusters are mounted on the hull of saidvessel below the water line and are adapted for dynamic positioning ofsaid vessel.
 17. A pipelaying vessel according to claim 15, wherein saidpipe take-off structure is adapted for arcuate movement about saidsupporting means to establish a range of entry angles of said pipelineinto the body of water of from about 20° to about 90°.
 18. A pipelayingvessel according to claim 15, wherein said pipe take-off structure isadapted for arcuate motion at a predetermined spaced distance from theperiphery of said pipeline support means.
 19. A pipelaying vesselaccording to claim 15, wherein said pipe take-off structure includespipe tensioning means as a part of one of said straighterner means. 20.A pipelaying system according to claim 15, wherein said pipeline layingdevice is adapted for transverse motion with respect to the vessellongitudinal axis.
 21. A pipelaying vessel according to claim 15,comprising at least one auxiliary operational line storage reel adaptedfor being operably secured to the deck of a vessel for unspooling anoperational line through said pipeline laying device.
 22. A pipelayingvessel according to claim 15, wherein at least two auxiliary operationallines storage reels are adapted to be operably mounted to the deck ofthe vessel, and wherein at least one of said auxiliary storage reelscontains a rigid walled pipeline for unspooling and laying out throughsaid pipeline laying device.
 23. A pipelaying vessel according to claim22, wherein said auxiliary storage reels are adapted for being mountedon the deck of the vessel between said reel for storage and layout of arigid walled pipeline and said pipeline laying device.
 24. A pipelayingvessel according to claim 15, wherein said pipeline laying device isadapted for receiving said pipeline as it is unspooled from the bottomof said reel.
 25. A pipelaying vessel according to claim 15, whereinsaid pipeline laying device is adapted for receiving said pipeline as itis unspooled from the top of said reel.
 26. A pipelaying vesselaccording to claim 15 including pipeline handling means supported bysaid pipe take-off structure and adapted for facilitating pipelineadjustments and connections.
 27. A pipelaying vessel according to claim26, wherein said pipe handling means comprises a work platform.
 28. Apipelaying system according to claim 26, wherein said pipe handlingmeans comprises a pipe clamping means.
 29. A method of unspooling andlaying out a pipeline into a body of water from a pipelaying systemwhich includes a laying device with a drum adapted for being mountedadjacent the stern of a vessel for rotation about a horizontal drumaxis, said method comprising the steps of:moving the pipeline off of astorage reel and past the drum around an arcuate turn defined by thesurface fo the drum; providing moving contact between the pipeline andthe drum with the pipeline and drum moving about the same axis; changingthe direction of movement of the pipeline from the vessel to a downwarddirection; straightening the pipeline subsequent to said moving step bycontact with a pipe take-off structure pivoting about the same axis asthe drum and providing three force points for the contact as thepipeline leaves the drum, with the three force points rotating about acommon axis as the downward direction is changed; and providing foradjustment of the pipeline water entry angle and providing for pipehandling changes within said laying system and laying out the pipelinefrom the vessel in a downward direction into the body of water.
 30. Themethod of unspooling a pipeline according to claim 29, including theadditional step of:providing longitudinal tension force in a directionsubstantially parallel to the pipeline subsequent to said moving step.31. The method of unspooling a pipeline according to claim 29 whereinsaid moving step is carried out by providing the laying device with apipeline supporting means which is adapted to provide moving contactwith said pipeline.
 32. The method according to claim 29, including thestep of:clamping the pipeline within the pipeline laying device toprovide for pipeline handling adjustments thereto.
 33. The methodaccording to claim 29, including the step of:clamping the pipelinewithin the pipeline laying device to provide for the inspection andrepairing of coating.
 34. The method according to claim 29, includingthe steps of:clamping the pipeline within the pipeline laying device tomaintain the pipeline in a fixed position with respect to said device;and providing for the installation of additional equipment selected fromthe class of valve, anode, transponder and survey marker equipment. 35.The method according to claim 29, wherein said unspooling step includesthe substep of moving the pipeline from the bottom of the reel into thelaying device.
 36. The method according to claim 29, wherein saidunspooling step includes the substep of moving the pipeline from the topof the reel into the laying device.